Aye, can see the argument, and certainly the more I think about it the less it seems totally inexplicable.
I think it's partly just the long-standing Guardiola-Messi association, and obviously Ronaldo is always positioned in direct opposition with Messi. Plus, obviously, Guardiola's teams tend to focus on players functioning as one part of the overall team, and Ronaldo has a fairly well-earned reputation as a solo player who wants the team to work around him, rather than him work for the team (in the one sense, no argument that he works very bloody hard as a player).
Maybe that's changed somewhat in recent seasons, though, or he could change and function more in a traditional team manner.
Or, as you suggest, maybe for one or two seasons there could be an odd marriage of the two, with Ronaldo acting as the goal-scoring focal point supplied by the creative players behind and around him. Would certainly be interesting to see how his inclusion affects the team dynamic and how some of the other City players react.